1. Field of the Invention
The present invention relates to an instrument display apparatus and more particularly to such a device which is adapted to produce a reflected image of an instrument in a windscreen or other similar assembly such that an operator may view same while simultaneously viewing out through the windscreen.
2. Description of the Prior Art
The development of a "HEADS-UP" display and which hereinafter will be referred to as HUD, had its genesis in the military aircraft field. As should be understood, in the operation of high speed aircraft such as fixed wing and rotary wing attack aircraft which are designed for combat, it is extremely hazardous for the pilot or a crew member such as a weapons officer to momentarily divert their attention from a hostile target or other point of interest in the immediate vicinity of the aircraft to read the dials, gauges, instruments, warning indicators, etc. on the assorted instrument panels and other displays positioned in various locations in the cockpit area but normally positioned below the average line of sight of the observer.
Those skilled in the art have long recognized that a HUD would be quite useful in such dangerous sports as high-speed motor car racing and could perhaps be helpful in the day-to-day driving activities of average motorists.
In operation, a HUD allows an operator of a conveyance such as all manner of overland vehicles, boats, aircraft, motorcycles, etc. to view substantially within their line of sight, critical instrumentation displays, such as speed, fuel consumption, oil pressure, etc. without substantially diverting their vision and attention from an area immediately in front of the vehicle. Further, such devices may be utilized in other applications such as in ticket booths, bank teller windows, etc.
The prior art is replete with several examples of HUDs which are designed for specific purposes and applications. Examples of prior art HUDs and related assemblies are shown in several U.S. Pat. Nos., particularly Steward 4,652,870; Banbury 4,560,233; Spooner 4,347,508; and Garner 4,453,163, to name but a few.
While it is speculated that the utilization of a HUD could conceivably improve the safe operation of a motor vehicle, the prior art devices have not been widely embraced for such an application. This has been due, in large measure, to the physical size and complexity of these prior art devices and their related assemblies. Further, commercial embodiments of HUDs installed in recently manufactured motor vehicles have revealed numerous inherent shortcomings which have detracted from their usefulness.
For example, one major drawback of the most recently manufactured HUDs is that the purchase price for same is usually cost prohibitive for most purchasers. Further, these devices do not operate effectively in many commonly encountered operational environments. By way of illustration, the commercially available HUDs individually employ digital, vacuum fluorescent displays, the light of which is reflected in an adjacent windscreen and which may be viewed by an operator. In one of the commercial embodiments, a windscreen viewing enhancement device is located somewhat out of the line of sight of the operator and which is adapted to reflect the light emitted by the display. Further, the other commercial embodiment employs, in combination with the digital vacuum fluorescent display, several optically precise mirrors which individually manipulate the light generated by the display in a predetermined fashion and projects it onto the adjacent windscreen. While these devices operate with some degree of success, they become inoperable in extremely bright light, or are difficult to read when the vehicle moves from a brightly lit environment into a shaded area.
Still another problem encountered with the prior art HUDs which have been designed for use in motor vehicles is the propensity for such devices to exhibit a characteristic inability to cooperate with other assemblies which are mounted in the area of the dashboard. Further, and with respect to one of the commercially available HUDs, the operator's eyes must be positioned within a very narrow cone of vision. If the operator moves his head outside of this cone, he will not be able to see the display. In addition, the prior art devices are not aesthetically appealing and therefore detract from the stylish appearance of the vehicle upon which it is installed.
Therefore, it has long been known that it would be desirable to have an instrument display apparatus which could be employed in all manner of overland vehicles, watercraft or aircraft, which could be manufactured and purchased at a relatively nominal cost, which is both highly efficient in operation and capable of operating in environments having various ambient light levels for the purpose of displaying an instrument face on an adjacent windscreen and within the line of vision of the operator, and which reduces to an absolute minimum the assorted problems inherent with the related prior art devices adapted to perform the identical function.